A study is proposed which will first define all the functional classes of ganglion cells in Rhesus monkey retina, in particular establishing how the fovea differs from other retinal areas. This information is still incomplete and has considerable importance for interpreting the single cell physiology of higher visual centers. Then combined extra - and intra-cellular recording and dye injection techniques will be used to link these physiological responses to anatomically defined ganglion cells. These results can elucidate the neural circuitry that determines the function of these different cells and facilitate knowing the central targets to which they project. Intra-cellular recording and staining will then be extended to include cells in the inner and outer nuclear layers of the retina. This can provide valuable information about the presynaptic circuitry of ganglion cells and the organization of spatial and color opponent mechanisms at an early stage in primate vision. Linking physiology with specific subsystems of ganglion cells, cone mechanisms and retinal areas, such as the fovea, provides important insights into the cellular basis of primate vision and facilitates understanding the physiology of higher visual centers and the psychophysics of human vision. It contributes to knowing how these specialized sites can be better examined by clinical diagnostic methods and why they may be selectively damaged by disease.